CHICAGO — An expert panel says there’s no rigorous evidence that digestive problems are more common in children with autism compared to other children, or that special diets work, contrary to claims by celebrities and vaccine naysayers.

Painful digestive problems can trigger problem behavior in children with autism and should be treated medically, according to the panel’s report published in the January issue of Pediatrics and released today.

“There are a lot of barriers to medical care to children with autism,” said the report’s lead author, Dr. Timothy Buie of Harvard Medical School. “They can be destructive and unruly in the office, or they can’t sit still. The nature of their condition often prevents them from getting standard medical care.”

Some pediatricians’ offices “can’t handle those kids,” Buie said, especially if children are in pain or discomfort because of bloating or stomach cramps. Pain can set off problem behavior, further complicating diagnosis, especially if the child has trouble communicating — as is the case for children with autism.

Autism is a spectrum of disorders affecting a person’s ability to communicate and interact with others. Children with autism may make poor eye contact or exhibit repetitive movements such as rocking or hand-flapping. About 1 in 110 U.S. children have autism, according to a recent government estimate.

More than 25 experts met in Boston in 2008 to write the consensus report after reviewing medical research. The Autism Society and other autism groups funded the effort but gave no input.

The report refutes the controversial idea that there’s a digestive problem specific to autism called “leaky gut” or “autistic enterocolitis.” The hypothesis was first floated in 1998 in a now-discredited study by British physician Dr. Andrew Wakefield. His paper tied a particular kind of autism and bowel disease to the measles vaccine.

The new report says the existence of autistic enterocolitis “has not been established.” Buie said researchers and doctors have avoided digestive issues in autism because of their connection with Wakefield’s disputed research, which set off a backlash against vaccines that continues to this day.

The new report calls for more rigorous research into the prevalence of digestive problems and whether special diets might help some children.

For now, the report states, available information doesn’t support special diets for autism.

Diets have been promoted by actress Jenny McCarthy, whose best-seller “Louder Than Words” detailed her search for treatments for her autistic son.

Nearly 1 in 5 of children with autism are on a special diet, according to a project that tracks what treatments parents are trying. Most of them were on diets that eliminate gluten, found in many grains, or casein, a protein in milk, or both, according to the Interactive Autism Network at the Kennedy Krieger Institute in Baltimore, Md.

The new report advises doctors to watch for nutritional deficiencies in patients with autism. It recommends a nutritionist get involved if a patient is on a special diet or only eats certain foods.